The invention relates to a process for obtaining and purifying pure α-mangostin from the rind of the fruit (“mangosteen”) of Garcinia mangostana. The mangosteen is the fruit of the Garcinia mangostana tree which originates from the Malaysian Archipelago, is widespread throughout the tropics and grows up to 15 m tall.
The fruits, which are roughly the size of a mandarin to an orange and are dark violet to brownish purple in colour, are highly prized on account of the intensely sweet acidic flavour of their flesh. The juice and the 8 mm thick, tough, leathery rind of the fruit have been shown to contain, among other things, the yellow xanthone derivatives α-mangostin and γ-mangostin. α-Mangostin is 1,3,6-trihydroxy-7-methoxy-2,8-bis-(3-methyl-but-2-enyl)-xanthen-9-one of formula 1, while γ-mangostin is the alcohol thereof which is free in the 7 position.

In the literature α-mangostin is described as a substance with an antihistamine and antiserotonin activity. Nowadays it is also used in the cosmetics industry. There is consequently a great demand for the pure compound.
Various suggestions for methods of purifying and isolating α-mangostin can be found in the literature. Thus, back in 1958, Yates et al. (J. Am. Chem. Soc. (1958) 80, 1691) dislcosed extraction of the fruit rinds to recover mangostin from Garcinia mangostana. However, this process, as in all subsequent publications, required chromatographic separation to isolate the α-mangostin after the plant material had been extracted, (Sakai et al. Chem. Pharm. Bull (1993) 41, 958; Govindachari et al. Tetrahedron (1971), 27, 3919; Gopalakrishnan et al. J. Nat. Prod. (1997) 60, 519, Chen et al. Planta Med. (1996) 62, 381; Iinuma et al. J. Pharm. Pharmacol. (1996) 48, 861)
The increasing demand for α-mangostin cannot be met by these methods. The aim of the present invention was therefore to provide a quick and simple method of isolating and purifying α-mangostin. Preferably, this process should be suitable for use on an industrial scale.